What motivates a serial killer?

Forensic psychologist Tom Powell told New England Cable News he sees in accused serial killer Israel Keyes a psychopath who was obsessed with controlling whatever or whomever he could.

"You see the pursuit of domination," Powell said. "[Someone] who gets off, really, on being on the top of the food chain, calling the shots."

Powell and the rest of Vermont learned Monday that Keyes confessed to traveling here 18 months ago with the intent to kill a stranger. Federal investigators said Keyes found what he wanted in Bill and Lorraine Currier of Essex, Vt., shooting the husband then sexually assaulting and strangling the wife.

After he was later arrested on suspicion he killed an Alaska teen, the FBI says Keyes admitted to murdering the Curriers, pointing authorities to an obscure spot in New York State where he hid the gun. Detectives wanted more info from Keyes, because they said he's linked to at least five other killings, but he took his own life in a jail cell Sunday. Reporters were not told how Keyes ended his life.

"Unfortunately, he suicided before he had a chance to fully confess," Powell said. "And I suspect that, in the end, was his ultimate power grab: that he was able to hold back that information knowing the rest of us would have these questions exactly as we're asking them now."

Federal officials described Keyes as a handyman who traveled the country for more than 10 years, extensively planning his crimes and driving hundreds of miles to find a target. The FBI said he would rob banks as one way of paying for his trips. In audio from March the FBI released Monday, Keyes described himself to a law enforcement interviewer as an enigma. "There's no one who knows me or who has ever known me who knows anything about me, really," Keyes said on the recording.

Norwich University criminologist Penny Shtull told NECN that unlike most murderers, who are driven by anger, revenge, or greed, male serial killers are looking for pleasure or a challenge. "A stranger can provide a thrill," Shtull said. "They have no attachment to them; they feel no remorse, no empathy, no guilt."

Shtull said one comfort Vermonters can take from learning Israel Keyes admitted to killing within this peaceful state's borders is that criminals like him are exceptionally rare. She said perhaps only a few dozen or up to 100 serial killers exist in the country.

Copyright 2012 byWPTZ All rights reserved. This material may not be published, broadcast, rewritten or redistributed.